Television transmitter



I April 30, 1940. K. SCHLESINGER TELEVISION TRANSMITTER Filed Jan. 22,1936 2 SheetsSheet 1 April 30, 1940. K. SCHLESINGER TELEVISIONTRANSMITTER Filed Jan. 22, 1936 2 Sheets-Sheet 2 dare/Mar r mam/LPatented Apr. 30, 1940 PATENT OFFICE TELEVISION TRANSMITTER.

Kurt Schlesinger, Berlin, Germany, assignor, by mesne assignments, toLoewe Radio, Inc., a corporation of New York 1 Application January 22,1936, Serial No. 60,295 In GermanyDecember 21, 1934 1 Claim.

Television transmitters for the transmission of films according to theinterlaced scannin method have already been described in earlierapplications. By this designation there is understood a method ofscanning images which consists in the fact that one and the same imageis scanned not merely once but a plurality of times with acorrespondingly smaller number of lines, and these different scanningphases are transmitted successively, staggered in relation to each otherto the extent of one line. In the application Ser. No. 36,008 whichmatured into Patent No. 2,186,931, Jan. 9, 1940, the applicant has setforth as means for obtaining an interlaced scanning of this kind aspecial, new-type doublespiral disc, characterised by the fact that atthe point of connection of the two spirals the radial advance is omittedonce to the extent of the width of one line. It was shown there that adouble-spiral disc of this nature in conjunction with a film moved inthe opposite direction results in a scanning operation with one singlerepetition and displacement to the extent of the width of one line,whereby all movements are of a uniform kind. v

In a later application Ser. No. 46,126, which matured into Patent No.2,147,555, Feb. 14, 1940, covering a form of embodiment it was shownthat to overcome the trapezoidal error resulting from the incongruity ofthe trapezoidal sectional area of a disc of this kind and therectangular reproduction area of the original image it is necessary toemploy an inclined optical system, which provides a congruenttrapezoidal reproduction of the film. In a further application there wasthen combined with these methods the self-synchronising image-pointmethod, which consists in the fact that at the edge of the image thererequires to be disposed a white starting line, the light intensity ofwhich exceeds that of the whitest portions of the image.

All of these single inventive ideas are insufiicient for practicalexecution until a large number of control knobs have been furnished in atransmission system of this character, so that the very precise opticalsettings and adjustments may actually be performed in the practicaloperation. There will be described in the present application atransmitter of this kind which has these possibilities and for thecomprehension of which the above remarks may serve as a preamble.

The novel features which I believe to be characteristic for my inventionare set forth with particularity in the appended claim. My invention,however, both as to its organization and method for operation togetherwith further objects and advantages thereof may be best understood byreference to the following description taken in connection with theaccompanying drawings in which in Fig. 1 there is shown the Nipkow disc,for instance the film picture twice over its area.

In Figs. 2 and. 3 there are illustrated details of the transmittermechanism with the novel features of my invention, Fig. 3 being asection of Fig. 2 along the line 3-3.

Referring now in particular to Fig. 1 there is shown the operation ofthe two-fold scanning of a film, which is moved evenly from the bot- 15tom towards the top. In this connection a scanning period is dividedinto six single positions I-6. In the position I there is alreadysituated a new film picture in the position assumed by the previouslytransmitted image in position 20 I. The double-spiral disc 8 is shown inthe correct operative position in relation to the movement of the filmll. Its sectional area is designated 9. The scanning image points areentered over the movement of the film. They are connected with eachother in broken lines by a curve II]. This curve represents a relaxationoscillation interrupted at the points 6--l or I. The height of thisrelaxation oscillation is equal to the height of the sectional area 9and 30 is designated h. In comparison therewith the height of thefilmimage is designatedI-I. In regarding Fig. 1 it will be apparent thatthe interlaced scanning will only be successful, that is to saythe twopart-scannings of the image will only correctly register, when theheight of the film reproduction H is greater to the extent of two linesthan the height of the sectional area h on the double-spiral disc 8.Expressed as formula:

Operations with a transmitter of this kind are, therefore, only possibleif the scale of the optical reproduction between film and. disc can beadjusted very finely until the above equation according to the inventionhas been fulfilled. In addition, however, a number of other conditionsmust be fulfilled as regards the position of the reproduction, which areenumerated in the following:

1. M etn'c-The scale of reproduction must be such that the height of thereproduction exceeds the sectional area on the disc by the width of twoimage points.

2. Parallam-I'he adjustment of a reproducing area, which fulfils thefirst condition, must be finely adjustable in such fashion towards thetop and the bottom that both towards the top and the bottom exactly oneline of the reproduction extends beyond the sectional area.

3. Trapezium.--The optical reproduction of the film area on the discmust be accompanied by a trapezoidal distortion, in which the anglebetween the inclined sides of the trapezium is exactly equal to theangle between two successive radii of the Nipkow disc.

4. Image phase.-The point of connection between two successive filmpictures during the movement of the Nipkow disc and'the film'mustcoincide with the connecting point between the two spirals on the Nipkowdisc exactly at that moment when the spirals replace each other'in thescanning operation.

5. Meridian condition.,The perpendicular line passing exactly throughthe centre of the imagemustat the same time out the axis of the Nipkowdisc. The movement of the film must beexactly parallel to thisperpendicular line.

The transmitter illustrated in Fig. 2 not only permits of theaccomplishment of these five conditions, which in their entirety:guarantee the transmission, without error, of the contents of the imageaccording to the interlaced scanning. method.

Figsc2 and 3 show inside view and cross sectiona transmission devicewhich permits of the adjustment of all of these conditions. The film, inthe manner known per se, is conducted from asupply reel ll overa-conveying roller l2 and then enters the .track I 3. With this filmtrack there is firmly connecteda feed roller l4, so that the film alwaysruns smoothly on to the slides l3. A take-up roller [5, which is alsofirmly connected with [3, takes up the film smoothly and conducts it toa secondconveying roller l5 firmly connected with the casing. Followingthereon the film may be conducted throughthe sound deviceto the secondsupply reel. To fulfil the metric condition I the gate 13 is mounted ona pivot H, which in turn belongs to a sliding member I8. This member I8is capable of being displaced in elongated apertures l8 exactly in thedirection of the reproducing ray of light. The displacement is finelyadjustable by means of screws'and spindles (not shown). The Nipkow disc8 and the shutter diaphragm 20 are driven by synchronising motors 8' and20 respectively. By increasing the spacing between film and disc toproject a gradually decreasing reproduction on 8, which may always beadjusted to be sharp by readjustment of the shiftable lens l9.

To fulfil the second parallax condition there is employed a verticalspindle 2|. The spindle 2| moves upwards and downwards a diaphragm 22close the plane of the film [3. After, therefore, the lighted imagesection has been correctly adapted in size and position to the sectionalarea of the disc its trapezoidal form must be adapted to'that ofthe-disc 8. For this purpose there is provided the journal H, thecentre-point of which lays exactly in the plane of the film [3. Theentire film track 13 may accordingly be turned about thisjournal I! andfinally the correct inclination once and for all fixed by the screw 23.In addition, however, according to the invention,.the entire opticalpassage. of the rays must be capable of being adjustably tilted inrelation to the horizontal. This is possible in any case in the majorityof machines employed for kinematographic projection. The inclination inrela tion to the horizontal embraces the slide I8 and the-lens IS incommon, so that the light always remains co-axial to these parts. Withthese two possibilities of inclination there may be accomplishedquantitatively any desired trapezoidal distortion.

The fourth condition, image phase, is fulfilled by the interposition ofan excentrically mounted roller 24. The image mark is able to be madeco-phasal with the jumping-over point on the Nipkow disc 8 by adjustingthe BXCBID vtricity of 24.

I claim:

In a television'transmitter an arrangement for exactly adjusting theposition of the film gate relatively to the scanning means, saidarrangementcomprising a member which is horizontallyshiftable-foradjusting the distance of the film gate from the scanningmeans, a film gate adjustably pivoted on said member for varying theinclination of the film gate relatively to the lens system, and adiaphragm shift'able on the film gate in a directionparallel to saidfilm gate for adjusting the effective borders of the film gate.

KURT SCHLESINGER.

